The present invention relates to a detecting system or device for detecting an unexpected leakage of fuel evaporation gas mainly from a fuel tank constituting an automobile fuel supply device, and a method of detecting gas leakage by using the device.
Japanese Patent Publication (Kokai) No. 2001-12319 has disclosed a device for detecting leakage of fuel evaporation gas in a fuel tank constituting an automobile fuel supply device, i.e. a device for diagnosing leakage.
The device disclosed in Japanese Patent Publication (Kokai) No. 2001-12319 includes an air pump, a driving motor and surrounding pipes, thereby making the device complicated. In the device, the leakage is detected through an operation voltage of the driving motor of the air pump, thereby making it difficult to accurately detect the leakage. Further, it is necessary to start the air pump for detecting the leakage after an internal combustion engine is stopped, thereby wasting a battery and generating operation noise of the air pump after the internal combustion engine is stopped.
In view of the problems described above, an object of the present invention is to provide a device with a simple structure for precisely detecting an unexpected leakage of the fuel evaporation gas from the fuel tank.
Further objects and advantages of the invention will be apparent from the following description of the invention.